Spindle-oriented stop mechanism for machine tool

ABSTRACT

A stop mechanism for stopping the spindle of a machine tool in a preselected position. The drive mechanism for the spindle is deenergized by a signal from a tape-operated controller and the inertia of the drive system is permitted to drive the spindle till the energy of the system is dissipated. A second signal from the controller operates a system of electromagnetic clutches and gear trains to slowly drive the spindle till a sensing device feels a selected position of the spindle. The device then deenergizes the slow drive and the inertia of the system moves the spindle toward the selected position. A stop mechanism is operated to stop the slowly coasting mechanism and to lock the spindle in the selected position. In the event the spindle does not reach the selected position, the slow drive is again energized and the process of driving and coasting repeated till the position is secured.

United States Patent Sato et al.

Tanaka, No. 2211, Okura, Machidashi, Tokyo, both of Japan [22] Filed:Sept. 24, 1969 [21] Appl.No.: 860,716

[52] U.S.Cl ..192/146, 192/148 [51] lnt.Cl ..Fl6d 71/00 [58] FieldolSearch ..l92/146, 147, 148; 3l8/20.l02

[56] References Cited UNITED STATES PATENTS 1,265,529 5/1918 Schoenky..192/146 2,907,434 10/1959 Wenzel 3,265,946 8/1966 Johnson et al...318/20.l02 X 51 Jan. 25, 1972 Primary Examiner-Allan D. HerrmannAttorney-Harold L. Halpcrt [57] ABSTRACT A stop mechanism for stoppingthe spindle of a machine tool in a preselected position. The drivemechanism for the spindle is deenergized by a signal from atape-operated controller and the inertia of the drive system ispermitted to drive the spindle till the energy ofthe system isdissipated. A second signal from the controller operates a system ofelectromagnetic clutches and gear trains to slowly drive the spindletill a sensing device feels a selected position of the spindle. Thedevice then deenergizes the slow drive and the inertia of the systemmoves the spindle toward the selected position. A stop mechanism isoperated to stop the slowly coasting mechanism and to lock the spindlein the selected position. In the event the spindle does not reach theselected position, the slow drive is again energized and the process ofdriving and coasting repeated till the position is secured.

6 Claims, 9 Drawing Figures PATENTED M25 872 SHEET 10F 2 INVENTOR. Y vSac; BY Mi.

PATENTEU M25972 SHEET 2 BF 2 SPlNDLE-ORIENTED STOP MECHANISM FOR MACHINETOQlL This invention pertains to a spindle-oriented stop mechanism formachine tools.

Heretofore, a strong brake was applied to the main spindle or to otherrotating shafts in the transmission system to stop the main spindle in apreselected position. The drawback of this system lies in the enormousshock produced at the gears and the motor for instantaneous braking.This shock produces wear and consequently results in deterioration ofaccuracy and diminished life of the machine tool.

The object of this invention is to provide a machine tool with means forstopping the main spindle in preselected position so that a key mountedon the spindle always engages a key-way formed in the flange of thetool.

Another object of this invention is to provide a machine tool forstopping a spindle in a preselected stop position by means ofdisconnecting the drive system, driving the main spindle at a slow speedthen, when rotation by the inertia of the system is about to terminate,the main spindle is forced to stop in a predetermined position.

Still another object of this invention is to provide a spindleorientingsystem which barely shocks the gears and the motor when stopping themain spindle and thereby prevents, wear in the rotating parts anddeterioration in the accuracy of the machine tool.

These and other objects of the invention will become manifest uponreading the following description in conjunction with the accompanyingdrawings wherein:

FIG. 1 is a sectional side view of the speed-reducing transmissionsystem with some of the parts in section.

FIG. 2 is a front view of the main spindle and a part of the spindlehead.

FIG. 3 is a side view of a tool.

FIG. 4 is a section along 4-4 of FIG. 1.

FIG. Sis a section along 5-5 of FIG. 1.

FIG. 6 is a front view showing a first positioning device engaging thedisc of FIG. 4.

FIG. 7 shows a second positioning device engaging a second disc when thefirst positioning device engages a notch in the first disc.

FIG. 8 is a front view showing the second positioning device engagingthe second disc in the stop position.

FIG. 9 is a front view showing the first positioning device engaging thefirst disc when the second positioning device and second disc are instop position.

FIG. 1 shows main spindle 3 with tool I rotating at normal cuttingspeed. The slow speed-reducing gear train 42 is disengaged by the openedelectromagnetic clutch 43. Transmission gear train 12 rotates the mainspindle at normal cutting speed.

Shaft 2 of tool 1 is held in collet 4 of main spindle 3. Shaft 2 of tool1 has flange 5 formed with a key-way 6 which is engaged by a key 8fixedly mounted on spindle 3 by screw 7. Since key 8 engages key-way 6the tool cannot slip in collet 4 during the cutting operation due to thefrictional force of cutting. Collet 4 securely grasps tool shaft 2 bydraw bar 9. Main spindle 3 is rotatably mounted on the spindle head 10by bearing Ill.

Main spindle head 10 contains speed reduction transmission system 12 inchange gear casing 13. Drive shaft 16 is belt driven by motor 14 andbelts l5 and is supported by bearings 17, 18 in casing 13. Drive shaft16, has gears 19, 20, 21, all of different sizes, fixedly mountedthereon to engage gears 25, 26, 27, rotatably mounted on shaft 24 whichin turn is mounted on bearings 22, 23 in casing 13.

Each of the aforedescribed free-turning gears 25, 26,27 are connected byelectromagnetic clutches. When the clutches are disengaged the gearsfreely rotate on shaft 24. When one of the electromagnetic clutches isenergized, shaft 24 is driven by the gear so engaged.

Variable speed shaft 24 has gears 31, 32 of different diametersrotatable mounted, and small gear 33 fixedly mounted thereon. Gears 31,32 have electromagnetic clutches 34, 35, which, when unenergized, leavesgears 31, 32 free to rotate on shaft 24, and when energized, rotation ofshaft 24 is engaged to either gear 31 or 32.

Change gear casing 12 has another :speed change shaft 36 rotatablymounted on bearings 37, 38. This shaft 36 has gears 39, 40 fixedlymounted thereon which engage gears 31, 32. Gear 39 engages gear 41 whichis fixedly mounted on main spindle 3.

By energizing and deenergizing the various electromagnetic clutches, itis possible to change the combination of gears, and by controlling thespeed of the motor, it. is possible to obtain at least 18 differentspeeds of rotation of the main spindle 3. The engaging and disengagingof the various electromagnetic clutches is controlled by programmedsignals recorded on tape.

Variable speed shaft 36 has slow speed transmission system 42,consisting of electromagnetic clutch 43 and gear 44 rotatably mountedthereon and engaged to gear 33 on shaft 24. When clutch 43 is energizedand aforedescribed clutches 34, 35 are disengaged, electromagneticclutch 30 is engaged and rotation of gear 44 is transmitted to shaft 36,which rotates gear 39 which in turn rotates main spindle 3 through gear41 at a slow speed such as 40 rpm.

The signals controlling clutch 43 and other clutches to operate slowspeed transmission system 42 is controlled by signals programmed andrecorded on tape. Disengagement of clutch 43 which disconnects slowspeed drive system 43 is initiated by a signal from the firstpositioning device which will be described in detail later.

Main drive spindle 3 has fixedly mounted thereto by keys 45 a disc whichcomprises a collar 46 with ring 48 having a notch 47 on its peripherymounted thereon by screws.

The disc is engaged by roller 50 of the first positioning or sensingdevice 51 which is vertically slidably mounted on the top surface ofmain spindle housing in. body 53 by bolts 52. Roller 50 is rotatablymounted on holder 55 which is mounted on base 54. Roller 50 ispositioned to have a slight gap between disc 48. Two rods 56 are springloaded by springs 59 acting between rod heads 57 and bottom of springcavity 58, to always hold rods 56 upwards thus holding baseplate 54 withroller 50 so that it will not touch disc 48. Positioner body 53 has acylinder 60 and a piston 61 reciprocable therein and which is attachedto positioner base 54. Cylinder 60 has pipe 62 which permits entry orexhaust of pressurized fluid therefrom. When pressurized fluid enterscylinder 60, piston 61 is moved downwards so that roller 50 is pushedagainst disc 48 and engages notch 47. Entry of the pressurized fluidinto cylinder 60 is controlled by a signal from the tape control centerwith recorded tape.

One of the rods 56 has a contacting button 63 mounted thereon. Contact63 is held at a predetermined distance from switch 64 which is fixedlymounted on the side of positioner body 53. When roller 50 engages thenotch 47 in disc 48, contacting button 63 contacts switch 64 andactivates it to produce a signal which disengages clutch 43 in slowspeed transmission system 42. Simultaneously this signal also opens avalve to exhaust cylinder 60 of the pressurized fluid and activates thesecond positioning device, which will be described later.

Spindle shaft 3 has disc 68 fixedly mounted thereon by key 65 and has aV-shaped notch 67 formed on its periphery. Positioner device 71 hasroller which engages disc 68, said device is slidably mounted in body 76which is bolted by bolts 72 to the top surface of spindle head 10.Roller 70 is rotatably mounted on roller holder 75 which is mounted onpiston rod 73. A small gap is formed between roller 70 and the peripheryof disc 68. Cylinder cavity 77 is divided into an upper chamber 79 and alower chamber 80 by piston 78. Pipes 81, 82 are connected to eachchamber to fill or exhaust the chambers with pressurized fluid.Pressurized fluid is allowed to enter chamber 79 through pipe 81. Asignal from switch 64 of positioner device 51, activates a timer device(not shown) which in turn sends a signal, delayed by certain fixedamount, to the electromagnetic valve connected to pipe 81.

Contactor arm 83 is always held in the uppermost position where itcontacts switch 85 held by bracket 84 attached to cylinder body 76. Inthis position, switch 85 sends a signal indicating that roller 70 is notcontacting disc 68. Another contact switch 86 fixedly mounted on theside of cylinder body 76 is mounted at a distance such that when roller70 engages the V-shaped notch 67 in disc 68, contactor button 83 engageslower switch 86 to make contact, the signal therefrom initiates motionof piston rod 73 to return to the upper position.

The following is an explanation of the operation of the exampleillustrated in the drawings. The following operation is initiated byelectrical signals from a tape-controlled control device.Electromagnetic clutches 30, 34 are engaged while all other clutches aredisengaged (H6. 1). Rotation of drive shaft 16 is transmitted to themain spindle through gears 21, 27, variable speed shaft 24 and gears 31,39, 41. The main spindle 3 is rotated at the proper speed for cuttingoperation with tool 1. When the cutting operation is completed, a signalfrom the tape-controlled control device cuts off the electric powersupply to drive motor 14. The motor 14, speed change transmission system12, and main spindle 3 will coast to a stop. In this case the positionor orientation of the main spindle in stop position is indefinite.

The next signal issued from the tape-controlled device disengageselectromagnetic clutch 34, and engages electromagnetic clutch 43 of theslow speed transmission system 42. Simultaneously electric current isapplied to the motor 14. Motor 14 rotates to drive shaft 16. Rotation ofshaft 16 is transmitted to variable speed shaft 24 through gears 21, 27;variable speed shaft 36 is driven by gears 33, 44 and drives mainspindle 3 through gears 39 and 41. In this case the rotation of the mainspindle is a slow speed of, for instance, 40

Still another signal from the tape-controlled control device allowspressurized fluid to enter cylinder 60 through pipe 62, of the firstpositioning device. Pressurized fluid moves piston 61, base 54 androller 50 downwards to engage the periphery of disc 48 mounted on thespindle. When roller 50 engages notch 47, positioning device 51 islowered causing contact button 63 to contact switch 64 which in turnmakes contact to send a signal for disengaging electromagnetic clutch 43of the slow speed gear system 42. Simultaneously the supply ofpressurized fluid to cylinder 60 is cutoff and pipe 62 is opened toallow the escape of fluid from the cylinder and the power supply todrive motor 14 is cutoff. Piston 61 with rods 56 and base 54 is returnedto the lifted position by springs 59 and the first positioning device 51returns to its rest position. Disengagement of electromagnetic clutch 43of the slow speed transmission system 42 and opening of power supplycircuit to the main drive motor 14 causes main spindle 3 gears 31, 32,39, 41 and variable speed shaft 36 to coast to a halt by their in ertla.

A signal from switch 64 of the first positioning device 51 is delayed bya timer switch. Approximately 1.5 revolutions before main spindle 3comes to a stop, the delayed signal permits pressurized fluid to enterupper cylinder chamber 79 through pipe 81. Fluid pressure forces pistonrod 73 with roller 70 downwards so that roller 70 engages the peripheryof slowly turning disc 68. When notch 67 is engaged by roller 70, theroller is displaced downwards the same amount. When roller 70 engagesnotch 67 disc 68 is prevented from turning, contact arm 83 contactslower switch 86 which makes electrical contact to send a signalindicating that main spindle 3 has stopped at the desired orientedposition. Another signal initiates entry of pressurized fluid into thelower cylinder chamber and also initiates exhausting of the pressurizedfluid contained in upper chamber 79 through a hydraulic system controldevice.

When pressurized fluid enters lower cylinder chamber 80 piston rod 73rises and contact arm 83 engages upper limit switch 85, and causes it tomake contact. The signal derived from this contact cuts off thepressurized fluid entering lower cylinder chamber 80. A hydrauliccontrol device activates a valve to prevent leakage of the pressurizedfluid from the lower cylinder chamber and thus piston rod 73 ismaintained in the rest position.

If roller 70 of the second positioning device 71 does not engage withnotch 67 of disc 68, i.e., if main spindle 3 comes to a halt prior toroller 70 engaging notch 67, the second positioning device returns toits normal position and slow speed transmission 42 is activated and mainspindle 3 is slowly rotated and the aforedescribed operation duplicatedtill the spindle is brought to a stop in the oriented position.

What we claim:

1. A stop mechanism for stopping the spindle of a machine tool in aselected position comprising means for driving said spindle in a workingcycle, means responsive to a control signal for deenergizing saiddriving means, means responsive to a control signal after said spindlehas stopped rotating for driving the spindle at a speed lower than thespeed of rotation in said working cycle, sensing means responsive to acontrol signal for sensing a preselected position of said spindle todeenergize said lower speed driving means when said spindle is in saidpreselected position, means responsive to the said preselected positionof the spindle for energizing a locking means, and means responsive tothe selected position of the spindle for locking the spindle by saidlocking means in said selected position.

2. A stop mechanism as defined in claim 1 further including meansresponsive to a control signal for unlocking the spindle.

3. A stop mechanism as defined in claim 1 further including means formomentary reenergizing and deenergizing said lower speed driving meansto rotate the spindle to said selected position upon failure of thelocking means to lock the spindle in the said selected position.

4. A stop mechanism as defined in claim 1 wherein said sensing meanscomprises a cam secured to the spindle and a follower for engagementwith the cam, said cam being formed with a depressed portion forengagement by the follower.

5. A stop mechanism as defined in claim 2 wherein the locking meanscomprises a disc secured to the spindle, a notch in the periphery of thedisc, and a follower for engagement with the notch.

6. A stop mechanism as defined in claim 5 wherein the means forunlocking the spindle comprises a pair of contacts carried by thefollower, a pair of spaced fixed contacts for engagement by said pair ofcontacts, and means responsive to the closing of one pair of contactsfor withdrawing the follower from the notch and means responsive to thewithdrawn position of the follower for closing the other pair ofcontacts to retain the follower in the withdrawn position.

1. A stop mechanism for stopping the spindle of a machine tool in aselected position comprising means for driving said spindle in a workingcycle, means responsive to a control signal for deenergizing saiddriving means, means responsive to a control signal after said spindlehas stopped rotating for driving the spindle at a speed lower than thespeed of rotation in said working cycle, sensing means responsive to acontrol signal for sensing a preselected position of said spindle todeenergize said lower speed driving means when said spindle is in saidpreselected position, means responsive to the said preselected positionof the spindle for energizing a locking means, and means responsive tothe selected position of the spindle for locking the spindle by saidlocking means in said selected position.
 2. A stop mechanism as definedin claim 1 further including means responsive to a control signal forunlocking the spindle.
 3. A stop mechanism as defined in claim 1 furtherincluding means for momentary reenergizing and deenergizing said lowerspeed driving means to rotate the spindle to said selected position uponfailure of the locking means to lock the spindle in the said selectedposition.
 4. A stop mechanism as defined in claim 1 wherein said sensingmeans comprises a cam secured to the spindle and a follower forengagement with the cam, said cam being formed with a depressed portionfor engagement by the follower.
 5. A stop mechanism as defined in claim2 wherein the locking means comprises a disc secured to the spindle, anotch in the periphery of the disc, and a follower for engagement withthe notch.
 6. A stop mechanism as defined in claim 5 wherein the meansfor unlocking the spindle comprises a pair of contacts carried by thefollower, a pair of spaced fixed contacts for engagement by said pair ofcontacts, and means responsive to the closing of one pair of contactsfor withdrawing the follower from the notch and means responsive to thewithdrawn position of the follower for closing the other pair ofcontacts to retain the follower in the withdrawn position.